<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- bootstrap 样式 -->
    <!-- <link rel="stylesheet" href="./css/bootstrap.min.css"> -->
    <link href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/5.2.2/css/bootstrap.min.css" rel="stylesheet">
    <style>
        .red {
            background-color: red;
        }

        .yellow {
            background-color: yellow;
        }

        .blue {
            background-color: blue;
        }

        .green {
            background-color: green;
        }
    </style>
</head>

<body>
    <div class="container">
        <!-- 一行 -->
        <div class="row">
            <div class="col-lg-6 red">1-1</div>
            <div class="col-lg-6 green">1-2</div>
        </div>
        <!-- 一行 -->
        <div class="row">
            <div class="col-lg-4 blue">2-1</div>
            <div class="col-lg-4 yellow">2-2</div>
            <div class="col-lg-4 red">2-3</div>
        </div>

        <div class="row">
            <div class="col-lg-6">
                <div class="btn-group">
                    <button type="button" class="btn btn-default">Left</button>
                    <button type="button" class="btn btn-default">Middle</button>
                    <button type="button" class="btn btn-default">Right</button>
                    <button type="button" class="btn btn-default">Right</button>
                </div>
                <button type="button" class="btn btn-primary">Danger</button>
            </div>

            <div class="col-lg-6">
                <form role="form">
                    <div class="form-group">
                      <label for="exampleInputEmail1">Email address</label>
                      <input type="email" class="form-control" id="exampleInputEmail1" placeholder="Enter email">
                    </div>
                    <div class="form-group">
                      <label for="exampleInputPassword1">Password</label>
                      <input type="password" class="form-control" id="exampleInputPassword1" placeholder="Password">
                    </div>
                    <div class="form-group">
                      <label for="exampleInputFile">File input</label>
                      <input type="file" id="exampleInputFile">
                      <p class="help-block">Example block-level help text here.</p>
                    </div>
                    <div class="checkbox">
                      <label>
                        <input type="checkbox"> Check me out
                      </label>
                    </div>
                    <button type="submit" class="btn btn-default">Submit</button>
                  </form>
            </div>
        </div>
    </div>
</body>

</html>